Elastomeric compositions containing olefin-acrylic ester copolymer

ABSTRACT

Elastomeric compositions comprising 1 part by weight of at least one curable elastomer and 0.01 to 100 parts by weight of at least one copolymer having olefin and acrylic ester monomer units as the main constituents, which possess improved properties in tackiness, processability, oil resistance, thermal resistance, weathering resistance and the like.

This is a division of application Ser. No. 279,289 filed Aug. 10, 1972,now U.S. Pat. No. 3,833,689, which is a continuation of application Ser.No. 29,276, filed Apr. 16, 1972, now abandoned.

The present invention relates to elastomeric compositions comprisingolefin-acrylic ester copolymers and curable elastomers. This inventionalso relates to co-curable elastomeric compositions comprising curableolefin-acrylic ester copolymers and rubbers.

In the blending of polymers, there is very often observed insufficientcompatibility. Still, no favorable co-curability can be expected in theinsufficient blending if the cured rubber is aimed. For instance,favorable results of curing are difficult to be attained by blending anelastomer having polar group for the purpose of improving the poorsolvent resistance of hydrocarbon rubbers. There are some syntheticrubbers of which application is restrained because of inferiorities ofproperties such as tackiness and processability in the uncured state ofthe compound used. Therefore, it is frequently requested to incorporatea compound having a polar group to the synthetic rubber without loss ofthe inherent properties of the rubber, but practically such a suitablecompound is difficult to be found. As results of investigations on themethod of admixing an ester compound with various elastomers, thepresent inventors have found that an olefin-acrylic ester copolymer issuccessfully compatible and blendable with a broad scope of elastomersand that the resultant compositions can be cured without accompanyingdeteriorations of properties of the cured products. Thus, the presentinvention has been established.

Accordingly, a basic object of the present invention is to provide anelastomeric composition containing a copolymer having olefin and acrylicester monomer units as main constituents and at least one curableelastomer. Especially, the invention provides an elastomeric compositioncontaining 0.01 to 100 parts by weight of olefin-acrylic ester copolymeron the basis of 1 part by weight of curable elastomer. A special objectof the present invention is to provide a co-curable compositioncomprising a curable olefin-acrylic ester copolymer and at least onecurable elastomer. A further object of the present invention is toprovide a process for preparing an elastomeric composition containingolefin-acrylic ester copolymer and curable elastomer.

The olefin used in the copolymer of this invention is effective forincreasing the affinity for hydrocarbon elastomers and thus the presentcopolymers are superior to the acrylic ester homopolymers. The polarester group brings to the elastomer improvements of tackiness, oilresistance, chemical resistance, weathering resistance and agingresistance. It is one of the important effects on the present inventionthat there has been overcome the defects including poor tackiness andill processability of the uncured elastomeric compound of which manyconventional synthetic rubbers are suffered. Of synthetic rubbers,ethylene-propylene terpolymers and butadiene-styrene copolymers showparticularly poor tackiness and ill processability in the uncuredelastomeric compound, of which improvement is desired. The said defectscan be now overcome by using the olefin-acrylic ester copolymers of thisinvention which are well compatible with those elastomers, and there isobserved no deterioration on the properties of the cured products.

It is another advantage of the elastomeric compositions of thisinvention that the olefin-acrylic ester copolymer has an affinity for alarge number of elastomers and is blendable with them successfully. Theolefin-acrylic ester copolymers including unsaturated group aresulfur-curable, and the compositions including these copolymers areco-curable with the opponent elastomer whereby further enhancedimprovements are attained.

It is one of the most important points in the present invention that theolefin-acrylic ester copolymers can be incorporated with a wide range ofrubbers from low-unsaturated rubbers to diene rubbers having highunsaturation to give co-cured elastomers having sufficiently goodmechanical strengths. Heretofore, it has been easy to co-cure alow-unsaturated rubber and other low-unsaturated rubber or a dienerubber and other diene rubber, but it has been difficult to co-cure alow-unsaturated rubber with a diene rubber. For instance, EPDM rubberhas not been obtained co-cured materials with diene rubbers having goodproperties, and there has been many problems. In such circumstances, thecompositions of the present invention are of interest and important inthe practical points of view.

As elastomers which can be combined with the olefin-acrylic estercopolymers, there are exemplified sulfur-curable or amine-curablevarious synthetic elastomers and natural elastomers includingethylene-propylene rubber, butyl rubber, butadiene-styrene rubber,polybutadiene rubber, butadiene-acrylonitrile rubber, polyisoprenerubber, natural rubber, acrylic rubber, chloroprene rubber, halogenatedethylene-propylene rubber and halogenated butyl rubber. Above all,hydrocarbon rubbers such as ethylene-propylene-diene rubber, butylrubber or butadiene-styrene rubber are more favorable for combinationwith the olefin-acrylic ester copolymers. The elastomeric component maybe used in a mixture of one or more sorts of these rubbers.

Since the olefin-acrylic ester copolymer of this invention is combinedwith an elastomer to form an elastomeric composition, the olefin-acrylicester copolymer having a low secondary transition point may be favorablyused. Although an acrylic ester homopolymer shows poor compatibilitywith synthetic elastomers or natural rubber, the olefin component in thecopolymer increases the affinity for hydrocarbon elastomers. From thismeaning, there may be favorably used such olefins as form a polymerhaving a low secondary transition point. Such a favorable olefininvolves an olefinic hydrocarbon and their halogenated compoundcontaining 2 to 20 carbon atoms, more favorably α-olefin containing 3 to8 carbon atoms. Diolefins and halogen-containing olefins and dieneswhich can be converted into elastomers readily may be used, too. Inthese cases, the copolymers of diolefins or halogenated olefins withacrylic esters are sulfur-curable or amine-curable. In these olefins,isobutylene and propylene are especially useful. Examples of theolefins, that is, are isobutylene, propylene, ethylene, butene-1,pentene-1, 2-methylbutene-1, 2-methylpentene-1, hexene-1, butene-2,4-methylpentene-1, 2-methyl-4-phenylbutene-1, octadecene-1,1,3-butadiene, 1,3-pentadiene, isoprene, 1,4-hexadiene,1,3,5-hexatriene, chloroprene, β-methallyl chloride and2-methyl-4-chloropentene-1.

For the ester group in the acrylic ester which is copolymerized with theolefin, hydrocarbon groups containing 1 to 20 carbon atoms and theirhalogenated compounds are preferable. Examples of the hydrocarbon groupare alkyl, alkenyl, aryl, aralkyl, aralkenyl, alkylaryl, alkenylaryl,cycloalkyl and cycloalkenyl, and their halogenated groups. Inparticular, alkyl group having 1 to 10 carbon atoms is suitable forelastomers, and alkyl having 2 to 8 carbon atoms is more suitable.Examples of the acrylic ester are methyl acrylate, ethyl acrylate,propyl acrylate, allyl acrylate, crotyl acrylate, n-butyl acrylate,t-butyl acrylate, n-amyl acrylate, n-hexyl acrylate, 2-ethylhexylacrylate, cyclopentenyl acrylate, octadecyl acrylate, methallylacrylate, citronellyl acrylate, cinnamyl acrylate, o-tolyl acrylate,benzyl acrylate, cyclohexyl acrylate, norbornenylmethyl acrylate,2-chloroethyl acrylate, 3-chloropropyl acrylate, β-chloroallyl acrylate,methyl thiolacrylate and ethyl thiolacrylate. Still, there may be usedacrylic esters having a substituent such as a hydrocarbon group, ahalohydrocarbon group or a halogen atom at the α- or β-position of theacrylic acid.

As sulfur-curable copolymers, there are favorably used such copolymersas olefin and/or acrylic ester containing directly at least partially adouble bond to act as a sulfur-curing site. As unsaturated groups in thecomponent to be sulfur-curing site, there may be favorably usedcomponents having an internal double bond inert to the polymerizationbecause there is observed no formation of troublesome gels. Thus, it isfavorable to use acrylic acid unsaturated esters above describedillustratively as a sulfur-curing site.

Further, as co-monomer components affording the sulfur-curing site,there may be effectively used a rather small amount of monomersproducing a polymer having a higher secondary transition point. As suchco-monomers, there are exemplified various polyene hydrocarbons orhalohydrocarbons and acrylic acid unsaturated esters which are out ofthe scope of the olefin because of higher secondary transition point,and as the other comonomers, unsaturated ethers and acrylic acidunsaturated amides. These comonomers include divinylbenzene,p-isopropenylstyrene, p-allylstyrene, 5-ethylidene-2-norbornene,5-methyl-2,5-norbornadiene, dicyclopentadiene, 1,5-cyclooctadiene,6-methyl-4,7,8,9-tetrahydroindene, 4-vinylcyclohexene, aldrin,p-(1'-chloro-1'-propenyl)-styrene, 1'-propenyl vinyl ether, cyclohexenylacrylate and N-(1'-propenyl)acrylamide.

The olefin-acrylic ester copolymers having halogen atom are in generalamine-curable. For instance, halogen-containing acrylic esters andhalogen-containing olefins may be used at least partially forcopolymerization. Further, other halogen-containing compounds which canbe copolymerized with olefin and acrylic ester may be used as a thirdcomponent for copolymerization. Favorable examples of the thirdcomponent are halogen-containing unsaturated ethers including2-chloroethyl vinyl ether, 4-chlorobutyl vinyl ether and isobutyl2-chloroallyl ether, and halogenated olefins and halogen-containingcarboxylic acid unsaturated esters may be also used, too. Still, theremay be used other olefin-acrylic ester copolymers which are modified byusing the other co-monomers.

The olefin-acrylic ester copolymers in the elastomeric compositions ofthe present invention are prepared in an arbitrary method. Inparticular, copolymers having high molecular weight can be effectivelyprepared from olefin and acrylic ester via a complex of a Lewis acidsuch as metal halide with carbonyl groups of the ester. Thecopolymerization may proceed effectively in the presence of an organicmetal compound as an initiator. The important copolymers are alternatingones which may be prepared effectively by copolymerizing olefin andacrylic ester in the presence of an organic halide of aluminum or boron.Ethylenically unsaturated monomers having the other double bond or ahalogen atom may be used in addition to the olefin and acrylic ester togive multicomponent alternating interpolymers. The details of suchmulticomponent alternating copolymers were described in thespecification of French Pat. No. 1,528,220.

As the preferable olefin-acrylic ester copolymers of the presentinvention, there are copolymers derived from such olefins as isobutyleneand propylene and acrylic esters having ester groups selected fromethyl, n-butyl, 2-ethyl-hexyl and methyl esters, as main constituents.The copolymer using ethyl acrylate is suitable as an elastomer, and thecopolymers derived from esters having more than three carbon atoms (e.g.n-butyl ester, 2-ethylhexyl ester) are favorable for the improvement oftackiness. Compositions of the copolymer are desirable to be selected sothat the products are elastomeric, and there is ordinarily used acopolymer comprising 10 to 70 mole %, preferably 30 to 50 mole %, of theolefin component and 90 to 30 mole %, preferably 70 to 50 mole %, of theacrylic ester component. As a third component, other co-monomers can becopolymerized in an extent enough not to damage the elastomericproperties. In general, 0.1 to 30 mole %, preferably 0.5 to 10 mole %,of the co-monomer having two unsaturated groups or a halogen atom may beincorporated into the copolymer for working as a sulfur-curing site oran amine-curing site. Still, much more functional groups can beincorporated, e.g. for the purpose of increasing the mutual affinitywith diene rubbers or for the other purposes.

The most important copolymers in the present invention are the so-calledalternating copolymers wherein olefin and acrylic ester are combinedalternately, i.e. 50 mole % of olefin and 50 mole % of acrylic ester arecontained. In the multicomponent alternating copolymer wherein othercomonomers are incorporated as the third components, 50 mole % of Agroup monomers and 50 mole % of B group monomers are contained. Saidco-monomers are classified in A group and B group whether they reactsimilarly as olefin or as acrylic ester. The detailed descriptionsthereof appears in Japanese patent application Nos. 36745/1966,70976/1968 and 99858/1969. The A group monomers involve α-olefins,internal olefins, styrenes, other ethylenically unsaturated hydrocarbonmonomers, dienes, carboxylic acid unsaturated esters, unsaturated ethersand halogen-substituted compounds thereof, and the B group monomersinvolve acrylonitrile, acrylic acid, acrylic esters, acryloyl halides,acrylamides, their halogenated compounds and α- or β-substitutedcompounds thereof.

The copolymers in the present invention have in general high molecularweights and the intrinsic viscosity measured at 30°C in benzene solutionis in the range of 0.1 to 10 dl/g, preferably 0.5 to 7 dl/g.

The elastomeric compositions of the present invention comprise theolefin-acrylic ester copolymer and rubber in a free ratio. For instance,an elastomeric composition containing 0.01 to 100 parts by weight of theolefin-acrylic ester copolymer per 1 part by weight of the rubber ispractically valuable. When there are used non-curable olefin-acrylicester copolymers, 1 to 40 parts by weight, favorably 2 to 20 parts byweight, of the copolymer per 100 parts by weight of the elastomer may bepreferably used. The elastomeric compositions of this invention may beprepared by blending the whole components in a voluntary method, forinstance, with a roll mill, a Banbury mixer, a calender roll, a kneaderblender, or an extruder.

In the present invention, a co-curable elastomeric compositioncomprising a sulfur-curable olefin-acrylic ester copolymer and asulfur-curable elastomer is very important. In this case, the proportionof blending may be arbitrarily chosen, and every composition is useful.In particular, favorable elastomeric compositions are such elastomers assulfur-curable ethylene-propylene copolymer, butyl rubber andbutadiene-styrene copolymer, and particularly elastomeric compositionsincluding isobutylene-ethyl acrylate-acrylic unsaturated ester areuseful.

It is well known that sulfur-curable ethylene-propylene elastomer (EPDM)is hardly co-curable with diene elastomers such as butadiene-styrenerubber, polybutadiene and natural rubber. Thus, it is surprising thatco-cured elastomeric compositions having excellent mechanical propertiesin the cured state can be obtained by blending in sulfur-curableisobutylene-acrylic ester copolymer and EPDM in any proportion.

On the other hand, an elastomeric composition comprising anamine-curable elastomer and a halogen-containing olefin-acrylic estercopolymer can be co-cured by amine-curing, and halogen-containingolefin-acrylic ester copolymers may be also added to sulfur-curableelastomers for improving properties thereof.

The elastomeric compositions of this invention can be combined withvarious other components such as curing agents, sulfur, fillers,stabilizers and diluents.

Sulfur and sulfur-curing accelerators may be used for obtaining thesulfur-cured products from the curable elastomeric compositions of thisinvention. Such curing-accelerators involve various compounds inthiazole series, sulfenamide series, thiazoline series, thiuram series,dithiocarbamate series, aldehyde-amine series and guanidine series.Examples of the curing accelerators are 2-mercaptobenzothiazole,dibenzothiazyl disulfide, methylene-aniline-mercaptobenzothiazole,cyclohexylbenzothiazylsulfenamide, 2-mercaptothiazoline,tetramethylthiuram disulfide, tetramethylthiuram monosulfide, telluriumdimethyldithiocarbamate, zinc dimethyldithiocarbamate, zincdibenzyldithiocarbamate, zinc dibutyldithiocarbamate, dinitrophenyldimethyldithiocarbamate, butylaldehyde-aniline condensate, anddi-o-tolylguanidine. These compounds may be used alone or in a mixtureof more than one compound. A suitable curing-accelerator may be selectedaccording to the sort of elastomers, and there is used ordinarily 0.1 to5 parts by weight, favorably 0.5 to 2 parts by weight, of theaccelerator per 100 parts by weight of the elastomer. A suitable amountof sulfur is 0.1 to 5 parts by weight, favorably 0.5 to 2 parts byweight, per 100 parts by weight of elastomer.

Amine-curable compositions may be cured with a basic substance as anamine-curing agent. The amine-curing agents invole basic compoundshaving at least two nitrogen atoms such as aliphatic polyamines,heterocyclic compounds having at least two nitrogen atoms, their aminecondensates, such as ureas, thioureas, Schiff bases or carbamates. Theamine-curing may be favorably effected in the presence of sulfur.

Other spontaneous components may be added to the elastomericcompositions of the present invention, if desired. These componentsinvolve fillers such as carbon black, hard clay, fine-powdery silicicacid, artificial silicate and calcium carbonate; plasticizers such asprocess oil and resins; minerals such as zinc oxide, magnesia andtitania; stearic acid and antioxidants.

Practical and presently-preferred embodiments of the present inventionare illustratively shown in the following examples wherein parts are byweight.

EXAMPLE 1

An olefin-acrylic ester copolymer (50:50) (10 or 20 parts) was admixedwith ethylene-propylene-5-ethylidene-2-norbornene terpolymer (Royalene501, manufactured by Uniroyal Co., Ltd.) (100 parts) at 40° to 50°C bytwo rolls. To the resulting mixture, there were added and blended HAFcarbon black (50 parts), zinc oxide (5 parts), stearic acid (1 part),sulfur (1.5 parts), tetramethylthiuram monosulfide (1.5 parts) and2-mercaptobenzothiazole (0.5 part).

The obtained compound was passed through an aperture of rolls to give asheet (about 1 mm thickness), which was used as a test sample formeasurement of tackiness. The measurement was carried out using apick-up type tack meter (manufactured by Toyo Seiki Co., Ltd.) under thefollowing conditions: temperature, 25°C; loading weight, 500 g; loadingperiod, 10 seconds; peeling rate, 10 cm/minute.

The said sample product was cured under pressing at 150°C for 10 minutesand subjected to measurement of physical properties. The modulus at 200%elongation, tensile strength at break, elongation at break and hardnesswere measured at 20°C in a tensile rate of 500 mm/minute with a tensiletester (manufactured by Shimadzu Seisakusho Ltd.) according to theJIS-K-6301 method.

The used olefin-acrylic ester copolymers are shown in Table 1, and Table2 shows the tackiness and physical properties of the compositionscomprising olefin-acrylic ester copolymers andethylene-propylene-5-ethyliene-2-norbornene terpolymer.

                  Table 1                                                         ______________________________________                                        Sample                      Ratio of                                           No.   Composition of copolymer                                                                           monomeric [η]*)                                                           components                                        ______________________________________                                        I     Propylene-ethyl acrylate                                                                            50/50     4.25                                    II    Propylene-butyl acrylate                                                                            50/50     2.40                                    III   Isobutylene-ethyl acrylate                                                                          50/50     2.75                                    IV    Isobutylene-butyl acrylate                                                                          50/50     5.79                                    V     Isobutylene-2-ethylhexyl acrylate                                                                   50/50     3.65                                    VI    Pentene-butyl acrylate                                                                              50/50     3.45                                    ______________________________________                                         Note:                                                                         *) Measured at 30°C in benzene.                                   

                                      Table 2                                     __________________________________________________________________________                   Control                                                                            Embodiments of the invention                              __________________________________________________________________________    Ethylene-propylene-5-ethyli-                                                  dene-2-norbornene terpolymer                                                                 100  100                                                                              100 100                                                                              100 100                                                                              100 100                                                                              100 100 100 100 100               (parts)                                                                       __________________________________________________________________________    Copolymer                                                                           Sort*)   --   I  I   II II  III                                                                              III IV IV  V   V   VI  VI                      Amount (parts)                                                                         --   10 20  10 20  10 20  10 20  10  20  10  20                __________________________________________________________________________    Tackiness                                                                           (g/mm)   24.5 39.2                                                                             51.5                                                                              35.6                                                                             49.3                                                                              44.5                                                                             57.9                                                                              44.3                                                                             54.3                                                                              37.8                                                                              50.0                                                                              39.0                                                                              49.3              __________________________________________________________________________          200 % Modulus                                                           Physical                                                                            (kg/cm.sup.2)                                                                          90   86 84  82 81  80 79  83 81  86  78  84  75                properties                                                                          Tensile strength                                                              (kg/cm.sup.2)                                                                          203  192                                                                              189 196                                                                              190 191                                                                              188 194                                                                              189 190 182 189 179                     Elongation (%)                                                                         425  505                                                                              535 490                                                                              515 485                                                                              550 450                                                                              495 435 485 420 435               __________________________________________________________________________     Note:                                                                         *) Numerals correspond to those in Table 1.                              

EXAMPLE 2

Copolymer I, III or V as shown in Table 1 (10 or 20 parts) was admixedwith styrene-butadiene rubber (SBR 1,500, manufactured by JapanSynthetic Rubber Co., Ltd.) (100 parts) at 40° to 50°C by two rolls. Tothe resulting mixture, there were added and blended HAF carbon black (50parts), zinc oxide (5 parts), stearic acid (1 part), sulfur (2 parts)and N-cyclohexyl-2-benzothiazylsulfenamide (2 parts).

The tackiness and physical properties of the obtained compound weremeasured as in Example 1.

The results are shown in Table 3.

                                      Table 3                                     __________________________________________________________________________                   Control                                                                            Embodiments of the invention                              __________________________________________________________________________    Styrene-butadiene rubber                                                      (parts)        100  100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100                                        __________________________________________________________________________          Sort*)   --   I  I  III                                                                              III                                                                              V  V                                          Copolymer                                                                           Amount (parts)                                                                         --   10 20 10 20 10 20                                         __________________________________________________________________________    Tackiness                                                                           (g/mm)   28.6 41.5                                                                             59.3                                                                             43.2                                                                             61.1                                                                             45.5                                                                             69.8                                       __________________________________________________________________________          200 % Modulus                                                                 (kg/cm.sup.2)                                                                          41   39 37 37 31 40 35                                         Physical                                                                            Tensile strength                                                        properties                                                                          (kg/cm.sup.2)                                                                          233  221                                                                              215                                                                              219                                                                              205                                                                              227                                                                              213                                              Elongation (%)                                                                         700  785                                                                              805                                                                              795                                                                              850                                                                              755                                                                              800                                        __________________________________________________________________________     Note:                                                                         *)Numerals correspond to those in Table 1.                               

EXAMPLE 3

Fifteen parts of isobutylene-n-butyl acrylate-2-chloroethyl vinyl etherterpolymer (chlorine content, 2.53%; isobutylene, 49 mol %) (polymer A)or propylene-2-ethylhexyl acrylate-2-chloroethyl acrylate terpolymer(chlorine content, 1.67%; propylene, 47 mol %) (polymer B) were blendedwith ethylene-propylene-5-ethylidene-2-norbornene terpolymer (Royalene501) (100 parts) by two rolls. To the resulting mixture, there wereadded and blended HAF carbon black (50 parts), zinc oxide (5 parts),stearic acid (1 part), sulfur (1.5 parts), tetramethylthiuram disulfide(1.5 parts) and 2-mercaptobenzothiazole (0.5 part).

The obtained compound was passed through an aperture of rolls to give asheet (1 mm thickness), which was used as a test sample for measurementof tackiness. The measurement was carried out at 25°C with a pick-uptype tack meter (manufactured by Toyo Seiki Co., Ltd.).

The results are shown as follows:

    Composition of compound                                                                           Tackiness (g/mm)                                          ______________________________________                                        Ethylene-propylene-5-ethylidene-                                              2-norbornene terpolymer alone                                                                     25.1                                                      (Control)                                                                     Polymer A blended   60.3                                                      Polymer B blended   55.7                                                      ______________________________________                                    

EXAMPLE 4

Fifteen parts of isobutylene-n-butyl acrylate-2-chloroethyl vinyl etherterpolymer (polymer A) or propylene-2-ethylhexyl acrylate-2-chloroethylacrylate terpolymer (polymer B) were blended with butadiene-styrenecopolymer (100 parts) (SBR 1500, manufactured by Japan Synthetic RubberCo., Ltd.) by two rolls. To the resulting mixture, there were added andblended HAF carbon black (50 parts), zinc oxide (5 parts), stearic acid(1 part), sulfur (2 parts) and N-cyclohexyl-2-benzothiazylsulfenamide (2parts). The tackiness of the resultant compound was measured as inExample 3.

The results are shown as follows:

    Composition of compound                                                                          Tackiness (g/mm)                                           ______________________________________                                        Butadiene-styrene copolymer                                                   alone (Control)    30.6                                                       Polymer A blended  58.6                                                       Polymer B blended  55.2                                                       ______________________________________                                    

EXAMPLE 5

Ethylene-propylene-dicyclopentadiene terpolymer (propylene content, 26mol %; iodine value, 10.2; intrinsic viscosity measured at 70°C inxylene, 1.60 dl/g; Mooney viscosity, ML₁ ₊₄ 52) (25 parts),isobutylene-ethyl acrylate-allyl acrylate terpolymer (iodine value, 6.2;isobutylene, 48 mol %) (75 parts), HAF carbon black (50 parts), zincoxide (5 parts), tetramethylthiuram disulfide (1.5 parts),mercaptobenzothiazole (0.5 parts), sulfur (1.5 parts) and stearic acid(1 part) were blended by a plastograph. The resultant compound was curedunder pressing at 160°C for 40 minutes. On the tensile test, thefollowing results were obtained: tensile strength at break, 150 kg/cm² ;elongation at break, 310%. The cured product of the isobutyleneethylacrylate-allyl acrylate terpolymer alone gave the following results:tensile strength at break, 123 kg/cm² ; elongation at break, 180%.

The above results indicate that the blended composition is wellco-cured.

EXAMPLE 6

Ethylene-propylene-dicyclopentadiene terpolymer (propylene content, 26mol %; iodine value, 10.2; intrinsic viscosity measured at 70°C inxylene, 1.60 dl/g) (75 parts), isobutylene-ethyl acrylate-crotylacrylate terpolymer (iodine value, 7.3; isobutylene, 49 mol %) (25parts), FEF carbon black (50 parts), zinc oxide (5 parts), stearic acid(1 part), tetramethylthiuram monosulfide (1.5 parts),mercaptobenzothiazole (0.5 part) and sulfur (1.5 parts) were blended bya plastograph. The resultant compound was cured under pressing at 160°Cfor 40 minutes to give an elastomeric product having the followingphysical properties: tensile strength at break 205 kg/cm² ; elongationat break, 440%; 300% modulus, 145 kg/cm². The cured product was dippedin ASTM No. 1 oil at 150°C for 70 hours whereby the weight increase was117.3%. The cured product of the ethylenepropylene-dicyclopentadieneterpolymer alone showed 212.5% in weight increase.

These results mean that the co-cured composition holds enhanced oilresistance.

EXAMPLE 7

Isobutylene-allyl acrylate-ethyl acrylate terpolymer (isobutylene, 49mol %; allyl acrylate, 2.7 mol %; ethyl acrylate, 48.3 mol %) (50parts), butadiene-styrene copolymer (JSR-1500, manufactured by JapanSynthetic Rubber Co., Ltd.) (50 parts), zinc oxide (3 parts), FEF carbonblack (40 parts), stearic acid (2 parts), sulfur (1.5 parts) andN-cyclohexyl-2-benzothiazylsulfenamide (2 parts) were blended by tworolls. The resultant compound was cured under pressing at 150°C for 40minutes to give a co-cured elastomer being 141 kg/cm² in tensilestrength at break and 240% in elongation at break.

EXAMPLE 8

Isobutylene-allyl acrylate-ethyl acrylate terpolymer (isobutylene, 49mol %; allyl acrylate, 2.7 mol %; ethyl acrylate, 48.4 mol %) (50parts), butyl rubber (50 parts), zinc oxide (5 parts), HAF carbon black(50 parts), stearic acid (1 part), sulfur (1.5 parts),tetramethylthiuram disulfide (1.5 parts) and mercaptobenzothiazole (0.5part) were blended by two rolls. The resultant compound was cured underpressing at 160°C for 40 minutes to give a co-cured elastomer being 158kg/cm² in tensile strength at break and 480% in elongation at break.

EXAMPLE 9

Isobutylene-allyl acrylate acrylate-ethyl acrylate terpolymer(isobutylene, 49 mol %; allyl acrylate, 2.7 mol %; ethyl acrylate, 48.4mol %) (50 parts), butadiene-acrylonitrile copolymer (Hycar-1000 × 132)(50 parts), zinc oxide (5 parts), SRF carbon black (50 parts), sulfur(1.5 parts), stearic acid (1 part) and dibenzothiazole disulfide (1part) were blended by two rolls. The resultant compound was cured underpressing at 150°C for 40 minutes to give a co-cured elastomer being 128kg/cm² in tensile strength at break and 200% in elongation at break.

What is claimed is:
 1. An elastomeric composition comprising 1 part byweight of at least one curable elastomer selected from the groupconsisting of natural diene rubbers and synthetic conjugated dienerubbers and 0.01 to 100 parts by weight of at least one copolymer havingolefin and acrylic ester monomer units, said copolymer being composed of10 to 70 mole % of aliphatic α-olefin monomer units having 3 to 20carbon atoms, 90 to 30 mole % of acrylic monomer ester units, and 0.1 to30 mole % of a monomer unit selected from the group consisting of amonomer having at least one double bond and a monomer having at leastone halogen atom.
 2. A process for preparing an elastomeric compositionwhich comprises blending 1 part by weight of at least one curableelastomer selected from the group consisting of natural diene rubbersand synthetic conjugated diene rubbers with 0.01 to 100 parts by weightof at least one copolymer having aliphatic α-olefin and acrylic estermonomer units, said copolymer being composed of 10 to 70 mole % of theolefin monomer units having 3 to 20 carbon atoms and 90 to 30 mole %acrylic ester monomer units.
 3. An elastomeric composition comprising 1part by weight of at least one curable elastomer selected from the groupconsisting of natural diene rubbers and synthetic conjugated dienerubbers and 0.01 to 100 parts by weight of at least one copolymer havingaliphatic α-olefin and acrylic ester monomer units, said olefin unitshaving 3 to 20 carbon atoms, and said copolymer being composed of 10 to70 mole % of the olefin monomer units and 90 to 30 mole % of the acrylicester monomer units.
 4. An elastomeric composition which comprises 1part by weight of at least one cnjugated diene rubber and 0.01 to 100parts by weight of at least one copolymer having aliphatic α-olefin andacrylic ester monomer units, said copolymer being composed of 10 to 70mole % of aliphatic α-olefin monomer units having 3 to 20 carbon atoms,and 90 to 30 mole % of acrylic monomer ester units.
 5. An elastomericcomposition according to claim 4, wherein said copolymer furtherincludes 0.1 to 30 mole % of a different monomer unit selected from thegroup consisting of a monomer unit having at least two double bonds anda monomer unit having at least one halogen atom.
 6. An elastomericcomposition according to claim 3, wherein 1 part by weight of at leastone curable elastomer is combined with 0.01 to 0.4 part by weight of thecopolymer.
 7. An elastomeric composition according to claim 3, whereinthe olefin monomer unit in the copolymer is isobutylene or propylene. 8.An elastomeric composition according to claim 3, wherein the acrylicester monomer unit in the copolymer is ethyl acrylate, n-butyl acrylate,2-ethylhexyl acrylate or methyl acrylate.
 9. An elastomeric compositionaccording to claim 3, wherein the copolymer has alternating monomersequences.
 10. An elastomeric composition according to claim 3, whereinsulfur and a sulfur-curing agent are contained in the composition. 11.An elastomeric composition according to claim 3, wherein the olefinmonomer unit in the copolymer is isobutylene or propylene and theacrylic ester monomer unit in the copolymer is ethyl acrylate, n-butylacrylate, 2-ethylehexyl acrylate or methyl acrylate.
 12. An elastomericcomposition according to claim 3, wherein the copolymer has analternating sequence of olefin and acrylic ester monomer units.
 13. Anelastomeric composition according to claim 3, wherein the copolymer hasan intrinsic viscosity of 0.1 to 10 dl/g as measured in benzene at 30°C.14. An elastomeric composition according to claim 3, wherein the alcoholmoieties of the acrylic ester units have from 1 to 20 carbon atoms. 15.An elastomeric composition according to claim 14, wherein saidcomposition contains from 1 to 40 parts by weight of the copolymer per100 parts by weight of the elastomer.
 16. The elastomeric compositionaccording to claim 14, wherein said composition contains from 2 to 20parts by weight of the copolymer per 100 parts by weight of theelastomer.
 17. The elastomeric composition according to claim 4, whereinsaid conjugated diene rubber is selected from the group consisting ofnatural rubber, butadiene-styrene rubber, polybutadiene rubber,butadiene-acrylonitrile rubber, polyisoprene rubber, chloroprene rubberand butyl rubber.
 18. An elastomeric composition according to claim 3,wherein said olefin units have 3 to 8 carbon atoms.
 19. An elastomericcomposition according to claim 3, wherein the copolymer is asulfur-curable copolymer having at least one unsaturated bond.
 20. Anelastomeric composition according to claim 3, wherein the copolymer isan amine-curable copolymer having at least one halogen atom.
 21. Anelastomeric composition according to claim 3, wherein the copolymer is asulphur-curable terpolymer of olefin, acrylic ester and acrylicunsaturated ester.
 22. An elastomeric composition according to claim 3,wherein the copolymer is a terpolymer of olefin, acrylic ester anddienic hydrocarbon.
 23. An elastomeric composition according to claim 3,wherein the copolymer is a terpolymer of olefin, acrylic ester andhalogen-containing ester of acrylic acid or halogen-containingunsaturated ether.
 24. The elastomeric composition according to claim14, wherein said alcohol moiety is one derived from a hydrocarbon or ahalohydrocarbon.
 25. The elastomeric composition according to claim 14,wherein said alcohol moiety is an alkyl group.
 26. An elastomericcomposition according to claim 3, wherein said curable elastomer is asynthetic conjugated diene rubber.
 27. An elastomeric compositionaccording to claim 3, wherein said copolyer is an olefin/acrylate binarycopolymer.
 28. An elastomeric composition according to claim 27, whereinsaid curable elastomer is a synthetic diene rubber.
 29. An elastomericcomposition according to claim 1, wherein said aliphatic α-olefinmonomer unit has 3 to 8 carbon atoms.
 30. An elastomeric compositionaccording to claim 14, wherein said aliphatic α-olefin monomer unit has3 to 8 carbon atoms.
 31. An elastomeric composition according to claim3, wherein said composition contains from 1 to 40 parts by weight of thecopolymer per 100 parts by weight of the elastomer.
 32. The elastomericcomposition according to claim 3, wherein said composition contains from2 to 20 parts by weight of the copolymer per 100 parts by weight of theelastomer.
 33. An elastomeric composition according to claim 3, whereinsaid α-olefin unit is selected from the group consisting of isobutylene,propylene, butene-1, pentene-1, 2-methylbutene-1, 2-methylpentene-1,hexene-1, butene-2, 4-methylpentene-1 and octadecene-1.
 34. Anelastomeric composition according to claim 3, wherein the alkyl groupson the alkyl acrylate unit are halogenated.
 35. An elastomericcomposition according to claim 3, wherein said alkyl acrylate isselected from the group consisting of methyl acrylate, ethyl acrylate,propyl acrylate, allyl acrylate, crotyl acrylate, n-butyl acrylate,t-butyl acrylate, n-amyl acrylate, n-hexyl acrylate, 2-ethyl-hexylacrylate, cyclopentenyl acrylate, octadecyl acrylate, methallylacrylate, citronellyl acrylate, cinnamyl acrylate, o-tolyl acrylate,benzyl acrylate, cyclohexyl acrylate, norbornenylmethyl acrylate,2-chloroethyl acrylate, 3-chloropropyl acrylate, β-chloroallyl acrylate,methyl thiolacrylate and ethyl thiolacrylate.
 36. An elastomericcomposition according to claim 3, wherein the alkyl acrylate unit insaid copolymer is an acrylic acid unsaturated ester.
 37. An elastomericcomposition according to claim 3, wherein the olefin acrylate copolymeradditionally contains a polymerized monomer selected from the groupconsisting of diene monomers, halogen-containing unsaturated estermonomers and halogen containing unsaturated ether monomers.
 38. Anelastomeric composition according to claim 3, wherein said copolymeradditionally contains a polymerized monomer selected from the groupconsisting of divinylbenzene, p-isopropenyl-styrene, p-allylstyrene,5-ethylidene-2-norbornene, 5-methyl-2,5-norbornadiene,dicyclopentadiene, 1,5-cyclooctadiene,6-methyl-4,7,8,9-tetrahydroindene, 4-vinylcyclohexene, aldrin,p-(1'-chloro-1'-propenyl)-styrene, 1'-propenyl vinyl ether, cyclohexenylacrylate and N-(1'-propenyl) acrylamide.
 39. An elastomeric compositionaccording to claim 3, wherein said copolymer additionally includes apolymerized monomer selected from the group consisting of 2-chloroethylvinyl ether, 4-chlorobutyl vinyl ether and isobutyl 2-chloroallyl ether.40. An elastomeric composition according to claim 1, wherein the acrylicester units have from 1 to 20 carbon atoms.
 41. An elastomericcomposition according to claim 1, wherein said composition contains from1 to 40 parts by weight of the copolymer per 100 parts by weight of theelastomer.
 42. The elastomeric composition according to claim 1, whereinsaid composition contains from 2 to 20 parts by weight of the copolymerper 100 parts by weight of the elastomer.
 43. An elastomeric compositionaccording to claim 1, wherein said α-olefin unit is selected from thegroup consisting of isobutylene, propylene, butene-1, pentene-1,2-methylbutene-1, 1, 2-methylpentene-1, hexene-1, butene-2,4-methylpentene-1 and octadecene-1.
 44. An elastomeric compositionaccording to claim 1, wherein the alkyl groups on the alkyl acrylateunit are halogenated.
 45. An elastomeric composition according to claim1, wherein said alkyl acrylate is selected from the group consisting ofmethyl acrylate, ethyl acrylate, propyl acrylate, allyl acrylate, crotylacrylate, n-butyl acrylate, t-butyl acrylate, n-amyl acrylate, n-hexylacrylate, 2-ethyl-hexyl acrylate, cyclopentenyl acrylate, octadecylacrylate, methallyl acrylate, citronellyl acrylate, cinnamyl acrylate,o-tolyl acrylate, benzyl acrylate, cyclohexyl acrylate,norbornenylmethyl acrylate, 2-chloroethyl acrylate, 3-chloropropylacrylate, β-chloroallyl acrylate, methyl thiolacrylate and ethylthiolacrylate.
 46. An elastomeric composition according to claim 1,wherein the alkyl acrylate unit in said copolymer is an acrylic acidunsaturated ester.
 47. An elastomeric composition according to claim 1,wherein the olefin acrylate copolymer additionally contains apolymerized monomer selected from the group consisting of dienemonomers, halogen-containing unsaturated ester monomers and halogencontaining unsaturated ether monomers.
 48. An elastomeric compositionaccording to claim 1, wherein said copolymer additionally contains apolymerized monomer selected from the group consisting ofdivinylbenzene, p-isopropenylstyrene, 1-allylstyrene,5-ethylidene-2-norbornene, 5-methyl-2,5-norbornadiene,dicyclopentadiene, 1,5-cyclooctadiene,6-methyl-4,7,8,9-tetrahydroindene, 4-vinylcyclohexene, aldrin,1-(1'-chloro-1'-propenyl)-styrene, 1'-propenyl vinyl ether, cyclohexenylacrylate and N-(1'-propenyl) acrylamide.
 49. An elastomeric compositionaccording to claim 1, wherein said copolymer additionally includes apolymerized monomer selected from the group consisting of 2-chloroethylvinyl ether, 4-chlorobutyl vinyl ether and isobutyl 2-chloroallyl ether.